We plan to assess trait-markers for the development and course of depressive disorders, we propose to study individuals who were identified and diagnosed with depressive disorders in childhood, their offspring, and the adult siblings of the depressed probands; individuals who were identified and diagnosed with anxiety disorders in childhood and their offspring; and subjects with no history of child/adolescent psychiatric illness and their offspring. Assessments include baseline studies of central and autonomic nervous system functioning; studies of affect regulation; and studies of the startle response in selected subjects. Measures include brain electrical activity (EEG), autonomic nervous system activity (heart rate and vagal tone), facial electromyographic activity (EMG), emotion expression, trait emotion, and (in children) internalizing and externalizing problems. The Scheduling and Psychiatric Evaluation Core of the Program Project will assess psychiatric disorder, dates of onset and remission, and symptom severity ratings. We will test the hypothesis that depressive and anxiety disorders are associated with differential patterns of physiologic, behavioral, and emotional response; and individual differences in these patterns are associated with course and severity of disorder.